Conventionally, a liquefied petroleum gas such as a butane gas or the like is used as a fuel of a spark ignition type engine. At a time of injecting the fuel to an intake pipe line so as to supply to the engine, it is general to inject the fuel by regulating and vaporizing at a predetermined positive pressure in place of a liquid state. However, there is a case that a liquid fuel makes an intrusion into a regulator in a stop state of the engine and the fuel is injected to the intake pipe line in a state including the liquid fuel at a time of starting the engine. In the case mentioned above, an air-fuel mixture becomes too rich so as to generate a start fault and an operation malfunction of the engine.
Accordingly, there has been proposed a liquefied gas supply apparatus structured such that a shutoff valve shutting off a supply path at a time when the engine stops is provided on the liquefied gas supply path, and the liquefied gas is supplied only during the engine operation by opening the shutoff valve at a time of starting the engine (Japanese Patent Application Laid-Open No. 2002-70652). [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-70652